Spacer-damper for bundle conductors

ABSTRACT

Spacer-damper apparatus for bundle conductors includes an elongated, tubular spring member which telescopically receives a yieldable damping element. The damping element is formed from a rubber-like material characterized by the property of absorbing large quantities of energy upon deformation thereof which is released primarily as heat rather than in the rapid restoration of the element to its initial configuration. A pair of conductor gripping components are provided at opposite ends of the spring member for connection to spaced high voltage conductor cables.

United States Patent [191 Harmon Apr. 23, 1974 SPACER-DAMPER FOR BUNDLECONDUCTORS [75] lnventor: Robert W. Harmon, Centralia, Mo.

[73] Assignee: A. B. Chance Company, Centralia,

22 Filed: Sept. 16, 1969 21 Appl. No.: 858,337

[52] US. Cl 174/42, 174/146, 267/152,

267/74 [51] Int. Cl. H02g 7/14, H02g 7/12 [58] Field of Search 267/140,141, 152, 73, 267/74; 174/42 [56] References Cited UNITED STATES PATENTS1,918,135 7/1933 Resch 267/140 3,447,794 6/1969 Sudyk 267/140 1,610,77012/1926 Greene ..267/74 Primary Examiner-James B. Marbert Attorney,Agent, or Firm-Schmidt, Johnson, Hovey & Williams [5 7] ABSTRACTSpacer-damper apparatus for bundle conductors includes an elongated,tubular spring member which telescopically receives a yieldable dampingelement. The damping element is formed from a rubber-like materialcharacterized by the property of absorbing large quantities of energyupon deformation thereof which is released primarily as heat rather thanin the rapid restoration of the element to its initial configuration. Apair of conductor gripping components are provided at opposite ends ofthe spring member for connection to spaced high voltage conductorcables.

23 Claims, 7 Drawing Figures MTENTEDAPRZB um I 3806527v SHEET 2 BF 2 WWWV ATTORNEKfi.

1 SPACER-DAMPER FOR BUNDLE CONDUCTORS The present invention relates tohigh voltage power transmission equipment and particularly tospacerdamper apparatus for bundle conductors.

Wind-induced vibration is one of the most persistent operating hazardsof overhead transmission lines. Damaging oscillations traditionally havebeen divided into two categories, designated for convenience as eitheraeolian or galloping. The former is far more common and is probablyresponsible for most line damage. This type of oscillatory motion may beinduced by nothing more than a low velocity crosswind. Full-waveamplitudes with aeolian oscillations seldom exceed one or two conductordiameters, and half-loop lengths range from to 30 feet, with frequenciesin the range of 10 to 60 cycles per second.

Galloping conductors are far more rare and normally require the buildupof ice on the lee side of a conductor. Such a buildup of ice produces acrude airfoil which, in conjunction with the torsional response of theconductor, can produce a varied assortment of violent wave motions. Inextreme cases, amplitudes as high as 50 feet have been observed. Withsuch extreme motions, line outages and damage are inevitable.

Attempts to control aeolian vibrations along conventional singleconductor transmission lines has met with moderate success through theuse of dampers, conductor clamps with low inertia and high mobility,avoidance of resonant tower elements, and maintenance of low to moderateconductor tension. Control of galloping vibrations has, on the otherhand, met with little success.

The introduction of bundle conductor systems in recent years has blurredthe distinction between aeolian and galloping vibrations and hasgenerally aggravated the overall problem. Numerous instances have beennoted of bundle conductor systems vibrating in large amplitudes whichwould previously have been called galloping, when there was no icepresent. The simple system has become complex through aerodynamicinfluences and the interchange of energy between subconductors. Spacersand suspension points in bundle conductor systems provide directcommunication between the subconductors, multiplying the possible modesof vibration. For example, bundle conductors have been observedvibrating in a horizontal plane, a condition not previously encounteredwith single conductor systems. Another phenomena observed with bundleconductors is that often the windward conductors will hang quietly,doing little except to set up vortices in the air currents which arecarried across to agitate the other conductors into vibration. Nogeneral classification of bundle conductor vibration has beenestablished, but the need for an effective damping means is clearlyevident.

Prior damping devices have consisted largely of weights that weremounted on a single conductor clamp through flexible wire cables suchthat during vibration of the conductor, the weight tended to remainstationary or oscillate out of phase with the conductors and thevibration was dissipated through friction in the flexible cables. Theeffectiveness of such devices was hampered by the fact that theirrelatively high masses tended to result in the creation of nodal pointsat the location of the damper thus partially eliminating the energyabsorbing action of the damper. Furthermore,

such prior devices performed only a damping function and did not serveto maintain the spatial relationship of bundle conductors.

Spacers previously used with bundle conductors included thoseconstructed from helical rods which were wrapped around adjacentconductor cables and extended therebetween to maintain the cables inspaced relationship. While such devices had the desired low mass, theywere not capable of performing a substantial damping function.

Another device previously used was a rigid spacer provided with rubbermounts on the conductor gripping components. Problems associated withincreased masses were encountered with this type of device and it alsowas incapable of performing both a satisfactory spacing and dampingfunction. Both of the spacers described above were incapable ofresponding to the large scale motions that can occur along a highvoltage transmission line because of fault currents or ice dropping fromthe lines.

It is, therefore, the primary object of this invention to provide aspacer-damper assembly for bundle conductors which not only effectivelymaintains the conductors in spaced relationship without causing damageto the individual conductors, but also is capable of lessening thetendency of the conductors to vibrate, particularly in the formofdamaging oscillations.

Another important object of this invention is to provide a spacer-damperassembly for bundle conductors with the ability to respond to the largescale motions produced by fault currents or ice dropping from the lines.

A further important object of this invention is to provide spacer-damperapparatus for bundle conductors having a spring member for maintainingthe conductor cables in the desired spatial-relationship and anenergyabsorbing, yieldable element for controlling vibrations of thetype peculiar to bundle conductor systems.

As a corollary to the above object, it is also an object of thisinvention to provide spacer-damper apparatus as aforesaid wherein thedamping characteristics are enhanced by the provision of a yieldableelement characterized by the property of absorbing large quantities ofkinetic energy upon deformation thereof which is released primarily asheat rather than in restoration of the element to its initialconfiguration.

Yet another object of the invention is to provide spacer-damperapparatus for bundle conductors as previously described having asufficiently low mass such that the apparatus does not tend to createnodal points for the oscillating movements.

Still another object of the invention is to provide spacer-damperapparatus for bundle conductors that is capable of absorbing the energyof large scale motions such as those produced by fault currents, and isalso capable of restoring normal spacing following such disturbances.

An object of this invention is also to provide spacerdamper apparatusfor bundle conductors that can be inexpensively constructed, therebypermitting incorporation of the apparatus at every needed location andalso the provision of energy-absorbing elements at frequent intervalsalong the conductors.

Still other objects of the invention will become apparent or be madeclear from the following specification when read in light of theaccompanying drawings, wherein:

FIG. 1 is a side elevational view of one embodiment of the spacer-damperapparatus with portions of the same shown in cross section for purposesof illustration;

FIG. 2 is a fragmentary, side elevational view of the spacer-damperapparatus showing an alternative embodiment of the damping element,portions of the apparatus being shown in cross section for purposes ofillustration;

FIG. 3 is a fragmentary, side elevational view of still another form ofthe spacer-damper apparatus with the damping element being shown incross section for purposes of illustration;

FIG. 4 is a fragmentary, side elevational view of yet another embodimentof the spacer-damper apparatus with the damping element shown in crosssection for purposes of illustration;

FIG. 5 is a fragmentary, side elevational view of another alternativeembodiment of the apparatus with the damping element being shown incross section for clar- FIG. 6 is a fragmentary, side elevational viewof the spacer-damper apparatus showing an alternative form of theembodiment illustrated in FIG. I; and

FIG. 7 is a fragmentary, side elevational view of the apparatus with thedamping element being shown in cross section and illustrating analternative form of the embodiment shown in FIG. 2.

Referring to the drawing, and initially to the embodiment illustrated inFIGS. 1 and 6, the spacer-damper apparatus includes an elongated,tubular spring member such as a curvilinear coil spring 10 and a pair ofconductor-gripping components 12 and 14 connected to the spring 10 atopposite ends of the latter. An elongated, generally cylindrical,yieldable damping element 16 is telescopically received within thespring 10.

Each of the conductor-gripping components 12 and 14 includes a bodyportion 18, a keeper 20, and a leg portion 22 integral with the bodyportion 18. The body portion 18 and the keeper 20 are provided withmating flanges 24 and 26 respectively for cooperating with aconventional breakaway bolt assembly 28 to hold the components 12 and 14in gripping engagement with a conductor cable (not shown). Bolt assembly28 is of the breakaway type to not only insure proper tightening of thecomponents 12 and 14 around a pair of conductors but also to preventexcessive tightening which would result in damage to the conductors. Aspiral groove 30 along the outer surface of each of the leg portions 22receives the spiral convolutions of the respective ends of the coilspring 10.

It is preferred that the ends of the damping element 16 be disposed inabutting relationship to the leg portions 22 and bonded thereto by asuitable adhesive (as illustrated in FIG. 6) or otherwise secured toprevent any movement of the element 16 relative to the spring 10. Insome cases, however, where the conductor cables are not subjected toextremely excessive line motions, it has been found satisfactory to omitthe bond between the damping element 16 and the leg portions 22 andmaintain the element 16 in spaced relationship to the leg portions 22,as illustrated in FIG. 1.

In an alternative form of the invention as illustrated in FIGS. 2 and 7,an elongated, generally cylindrical damping element 32 is telescopicallyreceived within the coil spring 10, the latter being secured to the legportions 22 of a pair of conductor-gripping components in the samemanner as previously described for the embodiment of FIGS. 1 and 6. Inthe structure shown in FIGS. 2 and 7 however, the damping element 32 isprovided with a spiral groove 34 in the outer surface thereof having adepth less than the diameter of the spiral convolutions of the spring 10for complementally receiving the convolutions of the spring. Thisinhibits relative shifting of the spring 10 and the damping element 32and is particularly desirable when the ends of the damping element arespaced from the leg portions 22 as illustrated in FIG. 2. As shown inFIG. 7 however, the respective ends of the damping element 32 may bedisposed in abutting relationship to the leg portions 22 and securedthereto by a suitable adhesive.

A third alternative embodiment of the invention is illustrated in FIG. 3wherein a damping element 36 is shown telescoped within the coil spring10 between the leg portions 22 of the conductor-gripping components. Thedamping element 36 is bonded or otherwise secured to the leg portions22, and a spiral groove 38 in the outer surface thereof complementallyreceives the spiral convolutions of the coil spring 10. A secondelongated, generally tubular damping element 40 extends substantiallythe entire length of the spring 10 and has open ends for receiving therespective leg portions 22. The second damping element 40 is cast aroundthe spring 10 with the first damping element 36 disposed therein toprovide a configuration having a first spiral groove 42 in the innersurface thereof for receiving the spiral convolutions of the spring 10,and a second groove 44 for mating with the irregular surface of the legportions 22. It is to be understood, of course, that the second clampingelement 40 may be preformed around the spring 10 and the first dampingelement 36 subsequently disposed within the spring.

A fourth alternative embodiment of the invention is illustrated in FIG.5 wherein the spiral convolutions of the coil spring 10 are received bythe leg portions 22 of the conductor-gripping components, and a dampingelement 46 is cast in and around the coil spring 10 over substantiallythe entire length of the latter in a manner to receive the leg portions22 at opposite ends of the element 46. 1

In the further embodiment of the invention, as illustrated in FIG. 5,the spiral convolutions of the coil spring 10 are received by thegrooves 30 in the respective leg portions 22 and a generally tubulardamping element 48 is disposed in surrounding relationship to the coilspring 10. The damping element 48 is provided with a spiral groove 50 inits inner surface which receives the spiral convolutions of the spring10, and the ends of the damping element 48 are open for receiving therespective leg portions 22.

It is important that each of the damping elements 16, 32, 36, 40, 46 and48 be constructed of a dead rubber such-as butyl, silicone or otherrubber-like material that is characterized by the property of absorbinglarge quantities of energy upon deformation and which is releasedprimarily as heat rather than in the rapid restoration of the materialto its initial configuration. This assures that the apparatus willrespond to the large-scale motions produced by fault currents or thelike thereby permitting the individual conductor cables to approach eachother in a manner not possible with more rigid structures while at thesame time assuring the return of these cables to their normal spacedpositions as the kinetic energy is dissipated into heat.

An alternative form for the gripping components 12 and 14 is illustratedin FIGS. 3 and 7. In FIG. 3 it is seen that each of the leg portions 22is provided with alongitudinally extending tongue 52 which is embeddedwithin the damping element 36. A longitudinally extending tongue 54 ofslightly different configuration is illustrated projecting from each ofthe leg portions 22 and embedded in the damping element 32 in FIG. 7.The tongues 52 and 54 serve to mechanically grade out sharp flexing ofthe spring in the vicinity of the leg portions 22.

When the conductor-gripping components 12 and 14 of any of theembodiments of the invention are secured to a pair of adjacentconductors, the combination of the coil spring 10 and the yieldabledamping element of rubber-like energy-absorbing material providesspacer-damper apparatus that is particularly effective, in not onlycontrolling bundle conductor vibrations but is also capable ofresponding to the large-scale line motions along the conductors whichresult from fault currents or ice dropping from the lines to restorenormal spacing following such disturbances. The curvilinearconfiguration of the spring 10 assures that flexing thereof always takeplace in the same direction. This precludes undesirable slight unwindingof the individual conductor cables which could otherwise occur undercertain conditions if the spring 10 was allowed to flex in more than onedirection.

When a line motion disturbs the spatial relationship of two or moreconductors the kinetic energy is absorbed by the appropriate dampingelement as the latter is deformed. A large percentage of the energy isdissipated as heat and the remainder of the energy serves to slowlyreturn the damping element to its initial configuration and therebyrestore the conductors to their desired spatial positions. A verydesirable feature of the invention is the manner in which damping iseffectively accomplished without sacrifice in the flexibility of thespacer, i.e., the spring 10. This permits the conductors to approacheach other during a fault current or other I disturbance therebyavoiding physical stresses on the conductors which would inherentlyresult with a rigid structure where the conductors are held in spacedrelationship by generally unyielding members. Additionally, the inherentlightweightness of the spacer-damper of the present invention avoids thetendency for nodal points to form at the location of the apparatus as isthe case with damping structures employing suspended weights.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

l. Spacer-damper apparatus for bundle conductors comprising:

an elongated spring member;

a pair of conductor gripping components connected to the spring memberat opposite ends of the latter and constructed to be secured torespective conductors in clamping relationship thereto; and

an elongated, yieldable, damping element of a dead rubberlike materialdisposed between said compo- 6 nents, said material being characterizedby the property of absorbing the energy of motion imparted thereto byrelative movement of said conductors, primarily as heat rather thanrestoration of the element to its initial configuration.

2. The invention of claim 1, wherein said element comprises arubber-like material characterized by the property of absorbing largequantities of kinetic energy upon deformation thereof which is releasedprimarily as heat rather than in restoration of the element to itsinitial configuration.

3. The invention of claim 2, wherein said element comprises siliconerubber.

4. The invention of claim 2, wherein said element comprises butylrubber.

5. The invention of claim 1, wherein said spring member is ofcurvilinear configuration to assure flexing thereof in but onedirection.

6. The invention of claim 1, wherein said member includes an elongatedcoil spring, said element is received within said spring in abuttingrelationship to said components, and each of said components includes aleg portion provided with a spiral groove in the outer surface thereofcomplementally receiving the spiral convolutions of said spring and alongitudinally extending tongue embedded in said element.

7. The invention of claim 1, wherein said member is generally tubular,and an elongated, generally cylindrical, yieldable damping element istelescoped. into the member intermediate said components.

8. The invention of claim 7, wherein said member comprises an elongatedcoil spring and said element is provided with a spiral groove in theouter surface thereof which complementally receives the spiralconvolutions of said spring.

9. The invention of claim 7, wherein the respective ends of the elementare joined to respective components.

10. The invention of claim 7, wherein the respective ends of theelements are spaced from the respective components.

11. The invention of claim 7, wherein said damping element has a smoothuninterrupted surface.

12. The invention of claim 7, and a second elongated, yieldable dampingelement disposed in surrounding relationship to said member and thefirst mentioned damping element.

13. The invention of claim 12, wherein said member comprises anelongated coil spring and said second element is provided with a spiralgroove in the inner surface thereof which complementally receives thespiral convolutions of said spring.

14. The invention of claim 1, wherein said element is cast around saidmember.

15. The invention of claim 14, wherein said member comprises anelongated coil spring and said element is cast within and around saidspring.

16. The invention of claim 1, wherein-said element is generally tubularand disposed in surrounding relationship to said member.

17. The invention of claim 16, wherein said member comprises anelongated coil spring and said element is provided with a spiral groovein the inner surface thereof which complementally receives the spiralconvolutions of said spring.

18. Spacer-damper apparatusfor bundle conductors comprising:

an elongated coil spring member;

a conductor gripping component secured to each end of the member andconstructed to be secured to rerelationship which complementallyreceives the spiral convolutions of said spring member.

21. The invention of claim 18, wherein each of said conductor grippingcomponents includes a leg portion provided with a spiral groove in theouter surface thereof complementally receiving the spiral convolutionsof said spring member.

22. The invention of claim 21, wherein said leg portion is receivedwithin one end of said damping element.

23. The invention of claim 18, wherein said damping element extendssubstantially the length of said spring member in surroundingrelationship thereto.

1. Spacer-damper apparatus for bundle conductors comprising: anelongated spring member; a pair of conductor gripping componentsconnected to the spring member at opposite ends of the latter andconstructed to be secured to respective conductors in clampingrelationship thereto; and an elongated, yieldable, damping element of adead rubberlike material disposed between said components, said materialbeing characterized by the property of absorbing the energy of motionimparted thereto by relative movement of said conductors, primarily asheat rather than restoration of the element to its initialconfiguration.
 2. The invention of claim 1, wherein said elementcomprises a rubber-like material characterized by the property ofabsorbing large quantities of kinetic energy upon deformation thereofwhich is released primarily as heat rather than in restoration of theelement to its initial configuration.
 3. The invention of claim 2,wherein said element comprises silicone rubber.
 4. The invention ofclaim 2, wherein said element comprises butyl rubber.
 5. The inventionof claim 1, wherein said spring member is of curvilinear configurationto assure flexing thereof in but one direction.
 6. The invention ofclaim 1, wherein said member includes an elongated coil spring, saidelement is received within said spring in abutting relationship to saidcomponents, and each of said components includes a leg portion providedwith a spiral groove in the outer surface thereof complementallyreceiving the spiral convolutions of said spring and a longitudinallyextending tongue embedded in said element.
 7. The invention of claim 1,wherein said member is generally tubular, and an elongated, generallycylindrical, yieldable damping element is telescoped into the memberintermediate said components.
 8. The invention of claim 7, wherein saidmember comprises an elongated coil spring and said element is providedwith a spiral groove in the outer surface thereof which complementallyreceives the spiral convolutions of said spring.
 9. The invention ofclaim 7, wherein the respective ends of the element are joined torespective components.
 10. The invention of claim 7, wherein therespective ends of the elements are spaced from the respectivecomponents.
 11. The invention of claim 7, wherein said damping elementhas a smooth uninterrupted surface.
 12. The invention of claim 7, and asecond elongated, yieldable damping element disposed in surroundingrelationship to said member and the first mentioned damping element. 13.The invention of claim 12, wherein said member comprises an elongatedcoil spring and said second element is provided with a spiral Groove inthe inner surface thereof which complementally receives the spiralconvolutions of said spring.
 14. The invention of claim 1, wherein saidelement is cast around said member.
 15. The invention of claim 14,wherein said member comprises an elongated coil spring and said elementis cast within and around said spring.
 16. The invention of claim 1,wherein said element is generally tubular and disposed in surroundingrelationship to said member.
 17. The invention of claim 16, wherein saidmember comprises an elongated coil spring and said element is providedwith a spiral groove in the inner surface thereof which complementallyreceives the spiral convolutions of said spring.
 18. Spacer-damperapparatus for bundle conductors comprising: an elongated coil springmember; a conductor gripping component secured to each end of the memberand constructed to be secured to respective conductors in grippingrelationship thereto; an elongated yieldable damping element of a deadrubber-like material disposed between said components, said materialbeing characterized by the property absorbing the energy of motionimparted thereto by relative movement of said conductors, primarily asheat rather than restoration of the element to its initialconfiguration.
 19. The invention of claim 18, wherein said spring memberis of curvilinear configuration to assure flexing thereof in but onedirection.
 20. The invention of claim 18, wherein the element isprovided with a spiral groove in one surface thereof whichcomplementally receives the spiral convolutions of said spring member.21. The invention of claim 18, wherein each of said conductor grippingcomponents includes a leg portion provided with a spiral groove in theouter surface thereof complementally receiving the spiral convolutionsof said spring member.
 22. The invention of claim 21, wherein said legportion is received within one end of said damping element.
 23. Theinvention of claim 18, wherein said damping element extendssubstantially the length of said spring member in surroundingrelationship thereto.